Method of manufacturing roller bit structure



Aug. 29, 1939. R. R. cRuM 2,171,058

METHOD OF MANUFACTURING ROLLER BIT STRUCTURE Original Filed March 18, 1935 INVENTOR til Patented Aug. 29, 1939 UNITED STATES PATENT orrlcs METHOD OF MANUFACTURING ROLLER BIT STRUCTURE Roland R. Crum, Whittier, Califi, assignor of onefourth to Edwin A. Perkins and thrce-eighths to Frank W. Brainard, both of Whittier, Calif.

8 Claims.

This invention relates to a roller bit structure utilizing a plurality of roller cutters arranged to rotate about theirown axes which are transverse to the axis of rotation of the bit structure, and more particularly to a method of assembling such a bit structure.

This application is a division of a prior application filed March 18, 1935, in the name of R01- and R. Crum, for Roller bit structure, Serial No. 11,650, now Patent Number 2,116,561, May 10, 1938.

It is one of the objects of this invention to simplify and improve the construction of bits of this character.

It isanother object of this invention to provide an improved and simplified method of assembling bits of this character.

This invention possesses many other advan tages, and has other objects'which may be. made more easily apparent from a consideration of one embodiment of the invention. For this purpose there is shown a form in the drawing accompanying and forming part of therpresent specification. This form will now' be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to' be taken in a limiting sense, since the scope, of this invention is best defined by the appended claims;

Referring to the drawing:

Figure 1 is an elevation, partly in section, of a bit structure embodying the invention;

Fig. 2 is an enlarged sectional view taken along plane 22 of Fig. 1', the frame being shown as disposed in drilling position at the bottom of a hole being drilled; V

Fig. 3' is a. fragmentary'elevation of thelower portion of the bit structure;

Fig. 4 is a pictorial view of one of the arms utilized for supporting the transverse roller cutters; and

Fig. 5' is a sectional View of a modified form of the arm shown in Fig. 4.

The bit structure includes a frame I having an axis of rotation 2. This frame I is arranged to be disposed at the end of a drill. string; and for this purpose a' coupling or sub 3 is provided which joins the bit frame I to the. drill string. The drill string is adapted, as is well understood, to be rotated at the top o-fthe' well by appropriate power mechanism.

The coupling 3 is joined to the frame I by the aid of the taper threaded socket 4-, and is itself provided at its upper extremity with a tapered threaded extension 5 for coupling it to the bottom of a drill string.

In the, present instance, the bit frame I is provided with a plurality of roller cutters arranged in general as disclosed in the prior application Serial No. 715,504, filed March 14, 1934. Thus in the present instance, there are outside roller cutters 6 and 6, having downwardly directed axes converging toward the axis 2. These rollers are intended to contact with and out along the sloping annular zone I (Fig. 2). Inside of this zone a pair of roller cutters 8 and 9 is disposed. These roller cutters are both adapted to rotate about an axis 10, transverse to the axis 2 and intersecting that axis. These cutters 8 and 9 are adapted to abraid or cut along the flat zone II, as well as the upwardly projecting conical zone 12 forming the center of the bottom of the hole I8 being drilled.

The outside cutters 6 and 6' can be provided with any appropriately formed teeth or cutting elements, and are shown in this instance as carrying tapered V-shaped teeth. The cutters 8 ands can be provided with annular bands of V-shaped teeth, the outer bands I3 serving to out along the annular surface H. The other bands of teeth, such as I4 l5, l6 and I! are closer to the axis 2 and disposed along a taper, and within a conical envelope to out along the raised central portion [2 of the hole l8; These bands of tapered teeth M, l5, I6, and Il can out along overlapping zones on the surface I2.

The frame l, as. well as the coupling member 3, are provided with a central axial opening or aperture, such as [9, providing a water course forthe bit.

The outside cutters 6 and iican be appropriately supported on their axes by the aid of a pair of side arms 26' and 2t integral with the frame l. Such details of the bearing support for these outside cutters are described and claimed in' an application entitled Roller bit bearing structure filed heretofore in the name of Roland R. Crum, and since granted as Patent No. 2,061,141, dated November 17, 1936.

The manner in which the inside roller cutters 8 and 9 are supported can be best described in connection with Figs. 2 and 4. For this purpose a pair of arms 22 and-23 is provided. Each of these arms has an inwardly projecting pin member or stub shaft, comprising a large cylindrical portion 24 and a smaller cylindrical portion 25 separated by an abrupt shoulder 26. The pin may be formed integrally with the arm, as by casting, or drop forging, or it may be a separate piece secured to the arm in any convenient way, as by having an extension 50 secured in the arm by a weld 51 (see Fig. 5). The end of this pin structure 2425 is formed as a threaded extension 2'! terminating an an abrupt shoulder 28. The cylindrical surfaces 24 and 25 serve as inner races for sets of roller bearings 29 and 30. Furthermore, each of the arms 2223 is provided with a flange or boss 3| providing an abrupt surface at the extremity of the larger cylindrical surface 24. The pair of pin structures 2425 can be coupled together by a central coupling member or sleeve 32, threaded over both inner threaded portions 21. This coupling member 32 has abrupt end surfaces contacting at its ends with the abrupt surface 28, whereby it is assured that the two arms 2223 and its associated elements are held in definite spaced relationship. The arms 22 and 23 during the assembly of the roller cutters are separate from the bit frame I, and are later joined, after assembly of the roller cutters upon these arms, to the frame in a manner to be hereinafter described.

Each of the roller cutters 8 and 9 is provided with an abrupt end surface 33 abutting the flange 3|. Each of the cutters is furthermore provided with a pair of internal cylindrical surfaces 34' and 35, the internal cylindrical surface 34 being separated from the smaller cylindrical surface 35 by an abrupt shoulder 36. These internal cylindrical surfaces form respectively the outer races for the roller bearings 29 and 30. The inner ends of each of the roller cutters 8 and 9 is provided with a projection 37 having a clearance aperture with respect to the coupling member 32.

The rollers 29 and 30 are confined against axial movement, as shown most clearly in Fig. 2, by a plurality of abrupt shoulders. Thus for example, the rollers 29 are confined between the surfaces 3| and 36; and rollers 33 are confined between the abrupt surface 26 and the corresponding abrupt extremity of coupling member 32, as well as the overhanging edge 31 of the inner end of the cutters. These roller bearings are of sufficient length and number to sustain adequately the radial forces imposed upon the cutters during the process of drilling.

Furthermore, since these forces may tend to bring the inner adjacent faces of the cutters B and 9 together in frictional or rubbing engagement, it is preferred to deposit hard wearing surfaces or layers such as 38 on these inner faces as by welding. Such hard wearing surfaces can be formed, for example, of tungsten carbide composition, now commonly used to impart wear resisting qualities to surfaces of this character.

The manner in which the roller structure can be assembled can now be set forth. First of all, each of the cutteres 8 and 9 can be assembled with the rollers 29 and 3D, and then the pin structure 2425 can be passed into the cutters. When this is accomplished, the coupling member 32 can be turned in tightly on one of the threaded extremities 21. Then the threaded extremity 21 of the other arm can be inserted into the free end of the coupling member 32, and the entire arm 22 or 23 can be rotated to provide engagement of the threads between the coupling member and the threaded extremity.

After the transverse supported structure and cutters are so assembled, the arms 22 and 23 can be joined to the frame I. It is preferred to accomplish this connection by welding. For this purpose each of the arms 22--23 can be provided with a sloping surface 39 connecting the outside surface of the arm with a narrow flat surface 40. The ends of this flat surface 40 are joined by slanting surfaces 4| to the sides of the arms 2223. The surfaces 40 and 4| are arranged to contact respectively with corresponding surfaces 42 and 43 provided in the ends of the stubs 44 and 45 joined integrally to the frame I. These surfaces 42 and 43 serve to define a socket for the upper end of the arm. It is of course understood that the contacting surfaces are machined in order to provide accuracy and definiteness to the spacing of the arms.

Furthermore, each of the stubs 44 and 45 can be provided with upwardly slanting surfaces 46 and 41, defining with the surfaces 39 a tapered groove in which welded metal 48 can be built up to weld the parts together. The weld can be further strengthened by the welded in fillet 49, joining the inside surfaces of the arms 22-23 to the lower extremity of the stubs 44 and 45.

What is claimed is:

1. The process of manufacturing a roller bit structure which comprises integrally joining, to each of the two arms, a pin member, placing a roller cutter over each pin member, coupling the free ends of both pin members to provide a definite spacing between the arms, and then attaching said assembled arms and cutters to a frame.

2. The process of manufacturing a roller bit structure which comprises integrally joining, to each of two arms, a pin member, each of said pin members having a cylindrical surface forming an abrupt shoulder adjacent a terminal threaded projecting portion, placing a roller cutter over each cylindrical surface, coupling the two threaded portions so as to maintain said shoulders at a definite spacing, and then attaching said assembled arms and cutters to a frame.

3. The process of manufacturing a roller bit structure which comprises integrally joining, to each of two arms, a pin member, placing a roller cutter over each pin member, coupling the free ends of both pin members to provide a definite spacing between the arms, and then welding said assembled arms and cutters to a frame.

4. The process of manufacturing a roller bit structure which comprises integrally joining, to each of two arms, a pin member, each of said pin members having a cylindrical surface form ing an abrupt shoulder adjacent a terminal threaded projecting portion, placing a roller cutter over each cylindrical surface, coupling the two threaded portions so as to maintain said shoulders at a definite spacing, and then welding said assembled arms and cutters to a frame.

5. The process of manufacturing a roller bit structure which comprises, integrally joining a pin member to an arm, integrally joining a second pin member to a second arm, placing a roller cutter over each pin member, joining the free end of each pin to a coupling member to provide a definite spacing between the arms, and then attaching said assembled arms and cutters to a frame.

6. The process of manufacturing a roller bit structure which comprises, forming a pair of arms, each of said arms having a stub shaft formed therewith, placing a roller cutter over each of said shafts, attaching a coupling member to the free end of one of said shafts, attaching the free end of the other shaft to the coupling member to provide a definite spacing between the arms, and then attaching said assembled arms and cutters to a frame.

7. The process of manufacturing a roller bit structure which comprises forming a pair of arms, each of said arms including an integral stub shaft, each of said shafts having a threaded portion adjacent its free end, and a cylindrical surface forming an abrupt shoulder adjacent the threaded portion, placing a roller cutter over each cylindrical surface, attaching a coupling member to one of said threaded portions, attaching the other of said threaded portions to said coupling member so as to maintain a definite space between said shoulders, and. then attaching said assembled arms and cutters to a frame.

8. The process of manufacturing a roller bit structure which comprises forming a pair of arms, each of said arms including an integral stub shaft, the portion adjacent the free end of each shaft. being of reduced diameter, placing a roller cutter over each of the shafts, telescoping a connecting member over each of said portions to secure the arms together in definite spaced relation, and attaching said assembled arms and cutters to a frame.

ROLAND R. CRUM. 

